"All out—we climb the rest of the way on foot," Stevens told his companion, as the elevator stopped at the uppermost passenger floor. They walked across the small circular hall and the guard on duty came to attention and saluted as they approached him.

"I have orders to pass you and Miss Newton, sir. Do you know all the combinations?"

"I know this good old tub better than the men that built her—I helped calculate her," Stevens replied, as he stepped up to an apparently blank wall of steel and deftly manipulated an almost invisible dial set flush with its surface. "This is to keep the passengers where they belong," he explained, as a section of the wall swung backward in a short arc and slid smoothly aside. "We will now proceed to see what makes it tick."

Ladder after ladder of steel they climbed, and bulkhead after bulkhead opened at Stevens's knowing touch. At each floor the mathematician explained to the girl the operation of the machinery there automatically at work—devices for heating and cooling, devices for circulating, maintaining, and purifying the air and the water—in short, all the complex mechanism necessary for the comfort and convenience of the human cargo of the liner.

Soon they entered the conical top compartment, a room scarcely fifteen feet in diameter, tapering sharply upward to a hollow point some twenty feet above them. The true shape of the room, however, was not immediately apparent, because of the enormous latticed beams and girders which braced the walls in every direction. The air glowed with the violet light of the twelve great ultra-light projectors, like searchlights with three-foot lenses, which lined the wall. The floor beneath their feet was not a level steel platform, but seemed to be composed of many lenticular sections of dull blue alloy.

"We are standing upon the upper lookout lenses, aren't we?" asked the girl. "Is that perfectly all right?"

"Sure. They're so hard that nothing can scratch them, and of course Roeser's Rays go right through our bodies, or any ordinary substance, like a bullet through a hole in a Swiss cheese. Even those lenses wouldn't deflect them if they weren't solid fields of force."

As he spoke, one of the ultra-lights flashed around in a short, quick arc, and the girl saw that instead of the fierce glare she had expected, it emitted only a soft violet light. Nevertheless she dodged involuntarily and Stevens touched her arm reassuringly.

"All x, Miss Newton—they're as harmless as mice. They hardly ever have to swing past the vertical, and even if one shines right through you you can look it right in the eye as long as you want to—it can't hurt you a bit."

"No ultra-violet at all?"

"None whatever. Just a color—one of the many remaining crudities of our ultra-light vision. A lot of good men are studying this thing of direct vision, though, and it won't be long before we have a system that will really work."

"I think it's all perfectly wonderful!" she breathed. "Just think of traveling in comfort through empty space, and of actually seeing through seamless steel walls, without even a sign of a window! How can such things be possible?"

"I'll have to go pretty well back," he warned, "and any adequate explanation is bound to be fairly deep wading in spots. How technical can you stand it?"

"I can go down with you middling deep—I took a lot of general science, and physics through advanced mechanics. Of course, I didn't get into any such highly specialized stuff as sub-electronics or Roeser's Rays, but if you start drowning me, I'll yell."

"That's fine—you can get the idea all x, with that to go on. Let's sit down here on this girder. Roeser didn't do it all, by any means, even though he got credit for it—he merely helped the Martians do it. The whole thing started, of course, when Goddard shot his first rocket to the moon, and was intensified when Roeser so perfected his short waves that signals were exchanged with Mars—signals that neither side could make any sense out of. Goddard's pupils and followers made bigger and better rockets, and finally got one that could land safely upon Mars. Roeser, who was a mighty keen bird, was one of the first voyagers, and he didn't come back—he stayed there, living in a space-suit for three or four years, and got a brand-new education. Martian science always was hot, you know, but they were impractical. They were desperately hard up for water and air, and while they had a lot of wonderful ideas and theories, they couldn't overcome the practical technical difficulties in the way of making their ideas work. Now putting other peoples' ideas to work was Roeser's long suit—don't think that I'm belittling Roeser at all, either, for he was a brave and far-sighted man, was no mean scientist, and was certainly one of the best organizers and synchronizers the world has ever known—and since Martian and Tellurian science complemented each other, so that one filled in the gaps of the other, it wasn't long until fleets of space-freighters were bringing in air and water from Venus, which had more of both than she needed or wanted.

"Having done all he could for the Martians and having learned most of the stuff he wanted to know, Roeser came back to Tellus and organized Interplanetary, with scientists and engineers on all three planets, and set to work to improve the whole system, for the vessels they used then were dangerous—regular mankillers, in fact. At about this same time Roeser and the Interplanetary Corporation had a big part in the unification of the world into one nation, so that wars could no longer interfere with progress."

"With this introduction I can get down to fundamentals. Molecules are particles of the first order, and vibrations of the first order include sound, light, heat, electricity, radio, and so on. Second order, atoms—extremely short vibrations, such as hard X-rays. Third order, electrons and protons, with their accompanying Millikan, or cosmic, rays. Fourth order, sub-electrons and sub-protons. These, in the material aspect, are supposed to be the particles of the fourth order, and in the energy aspect they are known as Roeser's Rays. That is, these fourth-order rays and particles seem to partake of the nature of both energy and matter. Following me?"

"Right behind you," she assured him. She had been listening intently, her wide-spaced brown eyes fastened upon his face.

"Since these Roeser's Rays, or particles or rays of the fourth order, seem to be both matter and energy, and since the rays can be converted into what is supposed to be the particles, they have been thought to be the things from which both electrons and protons were built. Therefore, everybody except Norman Brandon has supposed them the ultimate units of creation, so that it would be useless to try to go any further...."

"Why, we were taught that they are the ultimate units!" she protested.

"I know you were—but we really don't know anything, except what we have learned empirically, even about our driving forces. What is called the fourth-order particle is absolutely unknown, since nobody has been able to detect it, to say nothing of determining its velocity or other properties. It has been assumed to have the velocity of light only because that hypothesis does not conflict with observational data. I'm going to give you the generally accepted idea, since we have nothing definite to offer in its place, but I warn you that that idea is very probably wrong. There's a lot of deep stuff down there hasn't been dug up yet. In fact, Brandon thinks that the product of conversion isn't what we think it is, at all—that the actual fundamental unit and the primary mechanism of the transformation lie somewhere below the fourth order, and possibly even below the level of the ether—but we haven't been able to find a point of attack yet that will let us get in anywhere. However, I'm getting 'way ahead of our subject. To get back to it, energy can be converted into something that acts like matter through Roeser's Rays, and that is the empirical fact underlying the drive of our space-ships, as well as that of almost all other vehicles on all three planets. Power is generated by the great waterfalls of Tellus and Venus—water's mighty scarce on Mars, of course, so most of our plants there use fuel—and is transmitted on light beams, by means of powerful fields of force to the receptors, wherever they may be. The individual transmitting fields and receptors are really simply matched-frequency units, each matching the electrical characteristics of some particular and unique beam of force. This beam is composed of Roeser's Rays, in their energy aspect. It took a long time to work out this tight-beam transmission of power, but it was fairly simple after they got it."

He took out a voluminous notebook, at the sight of which Nadia smiled.

"A computer might forget to dress, but you'd never catch one without a full magazine pencil and a lot of blank paper," he grinned in reply and went on, writing as he talked.

"For any given frequency, f, and phase angle, theta, you integrate, between limits zero and pi divided by two, sine theta d...."

"Hold it—I'm sinking!" Nadia exclaimed. "I don't integrate at all unless it is absolutely necessary. As long as you stick to general science, I'm right on your heels, but please lay off of integrations and all that—most especially stay away from those terrible electrical integrations. I always did think that they were the most poisonous kind known. I want only a general idea—that's all that I can understand, anyway."

"Sure, I forgot—guess I was getting in deeper than is necessary, especially since this whole thing of beam transmission is pretty crude yet and is bound to change a lot before long. There is so much loss that when we get more than a few hundred million kilometers away from a power-plant we lose reception entirely. But to get going again, the receptors receive the beam and from them the power is sent to the accumulators, where it is stored. These accumulators are an outgrowth of the storage battery. The theory of the accumulator is...."

"Lay off the theory, please!" the listener interrupted. "I understand perfectly without it. Energy is stored in the accumulators—you put it in and take it out. That's all that is necessary."

"I'd like to give you some of the theory—but, after all, it wouldn't add much to your understanding of the working of things, and it might mix you up, as some of it is pretty deep stuff. Then, too, it would take a lot of time, and the rest of your friends would squawk if I kept you here indefinitely. From the accumulators, then, the power is fed to the converters, each of which is backed by a projector. The converters simply change the aspect of the rays, from the energy aspect to the material aspect. As soon as this is done, the highly-charged particles—or whatever they are—thus formed are repelled by the terrific stationary force maintained in the projector backing the converter. Each particle departs with a velocity supposed to be that of light, and the recoil upon the projector drives the vessel, or car, or whatever it is attached to. Still with me?"

"Struggling a little, but my nose is still above the surface. These particles, being so infinitesimally small that they cannot even be detected, go right through any substance without any effect—they are not even harmful."

"Exactly. Now we are in position to go ahead with the lights, detectors, and so on. The energy aspect of the rays you can best understand as simply a vibration in the ether—an extremely high frequency one. While not rigidly scientific, that is close enough for you and me. Nobody knows what the stuff really is, and it cannot be explained or demonstrated by any model or concept in three-dimensional space. Its physical-mathematical interpretation, the only way in which it can be grasped at all, requires sixteen coordinates in four dimensions, and I don't suppose you'd care to go into that."

"I'll say I wouldn't!" she exclaimed, feelingly.

"Well, anyway, by the use of suitable fields of force it can be used as a carrier wave. Most of this stuff of the fields of force—how to carry the modulation up and down through all the frequency changes necessary—was figured out by the Martians ages ago. Used as a pure carrier wave, with a sender and a receiver at each end, it isn't so bad—that's why our communicator and radio systems work as well as they do. They are pretty good, really, but the ultra-light vision system is something else again. Sending the heterodyned wave through steel is easy, but breaking it up, so as to view an object and return the impulses, was an awful job and one that isn't half done yet. We see things, after a fashion and at a distance of a few kilometers, by sending an almost parallel wave from a twin-projector to disintegrate and double back the viewing wave. That's the way the lookout plates and lenses work, all over the ship—from the master-screens in the control room to the plates of the staterooms and lifeboats and the viewing-areas of the promenades. But the whole system is a rotten makeshift, and...."

"Just a minute!" exclaimed the girl. "I and everybody else have been thinking that everything is absolutely perfect; and yet every single thing you have talked about, you have ended up by describing as 'unknown,' 'rudimentary,' 'temporary,' or a 'makeshift.' You speak as though the entire system were a poor thing that will have to do until something better has been found, and that nobody knows anything about anything! How do you get that way?"

"By working with Brandon and Westfall. Those birds have got real brains and they're on the track of something that will, in all probability, be as far ahead of Roeser's Rays as our present system is ahead of the science of the seventeenth century."

"Really?" she looked at him in astonishment. "Tell me about it."

"Can't be done," he refused. "I don't know much about it—even they didn't know any too much about some of it when I had to come in. And what little I do know I can't tell, because it isn't mine."

"But you're working with them, aren't you?"

"Yes, in the sense that a small boy helps his father build a house. They're the brains—I simply do some figuring that they don't want to waste time doing."

Nadia, having no belief whatever in his modest disclaimer, but in secret greatly pleased by his attitude, replied:

"Of course you couldn't say anything about an unfinished project—I shouldn't have asked. Where do we go from here?"

"Down the lining of the hull, outside the passengers' quarters to the upper dirigible projectors," and he led the way down a series of steep steel stairways, through bulkheads and partitions of steel. "One thing I forgot to tell you about—the detectors. They're worked on the same principle as the lights, and are just about as efficient. Instead, of light, though, they send out cones of electromagnetic waves, which set up induced currents in any conductor encountered beyond our own shell. Since all dangerous meteorites have been shown to contain conducting material, that is enough to locate them, for radio finders automatically determine the direction, distance, and magnitude of the disturbance, and swing a light on it. That was what happened when that light swung toward us, back there in the prow."

"Are there any of those life-boats, that I've heard discussed so much lately, near here?" asked the girl.

"Lots of 'em—here's one right here," and at the next landing he opened a vacuum-insulated steel door, snapped on a light, and waved his hand. "You can't see much of it from here, but it's a complete space-ship in itself, capable of maintaining a dozen or fifteen persons during a two-weeks' cruise in space."

"Why isn't it a good idea to retain them? Accidents are still possible, are they not?"

"Of course, and there is no question of doing away with them entirely. Modern ships, however, have only enough of them to take care of the largest number of persons ever to be carried by the vessel."

"Has the Arcturus more than she needs?"

"I'll say she has, and more of everything else, except room for pay-load."

"I've heard them talking about junking her. I think it's a shame."

"So do I, in a way—you see, I helped design her and her sister-ship, the Sirius, which Brandon and Westfall are using as a floating laboratory. But times change, and the inefficient must go. She's a good old tub, but she was built when everybody was afraid of space, and we had to put every safety factor into her that we could think of. As a result, she is four times as heavy as she should be, and that takes a lot of extra power. Her skin is too thick. She has too many batteries of accumulators, too many life-boats, too many bulkheads and air-breaks, too many and too much of everything. She is so built that if she should break up out in space, nobody would die if they lived through the shock—there are so many bulkheads, air-breaks, and life-boats that no matter how many pieces she broke up into, the survivors would find themselves in something able to navigate. That excessive construction is no longer necessary. Modern ships carry ten times the pay-load on one-quarter of the power that this old battle-wagon uses. Even though she's only four years old, she's a relic of the days when we used to slam through on the ecliptic route, right through all the meteoric stuff that is always there—trusting to heavy armor to ward off anything too small for the observers and detectors to locate. Now, with the observatories and check-stations out in space, fairly light armor is sufficient, as we route ourselves well away from the ecliptic and so miss all the heavy stuff. So, badly as I hate to see her go there, the old tub is bound for the junk-yard."

A few more flights of stairs brought them to the upper band of dirigible projectors, which encircled the hull outside the passengers' quarters, some sixty feet below the prow. They were heavy, search-light-like affairs mounted upon massive universal bearings, free to turn in any direction, and each having its converter nestling inside its prodigious field of force. Stevens explained that these projectors were used in turning the vessel and in dodging meteorites when necessary, and they went on through another almost invisible door into a hall and took an elevator down to the main corridor.

"Well, you've seen it, Miss Newton," Stevens said regretfully, as he led her toward the captain's office. "The lower half is full of heavy stuff—accumulators, machinery, driving projectors, and such junk, so that the center of gravity is below the center of action of the driving projectors. That makes stable flight possible. It's all more or less like what we've just seen, and I don't suppose you want to miss the dance—anyway, a lot of people want to dance with you."

"Wouldn't you just as soon show me through the lower half as dance?"

"Rather, lots!"

"So would I. I can dance any time, and I want to see everything. Let's go!"

Down they went, past battery after battery of accumulators; climbing over and around the ever-increasing number of huge steel girders and bracers; through mazes of heavily insulated wiring and conduits; past mass after mass of automatic machinery which Stevens explained to his eager listener. They inspected one of the great driving projectors, which, built rigidly parallel to the axis of the ship and held immovably in place by enormous trusses of steel, revealed neither to the eye nor to the ear any sign of the terrific force it was exerting. Still lower they went, until the girl had been shown everything, even down to the bottom ultra-lights and stern braces.

"Tired?" Stevens asked, as the inspection was completed.

"Not very. It's been quite a climb, but I've had a wonderful time."

"So have I," he declared, positively. "I know what—we'll crawl up into one of these stern lifeboats and make us a cup of coffee before we climb back. With me?"

"'Way ahead of you!" Nadia accepted the invitation enthusiastically, and they made their way to the nearest of the miniature space-cruisers. Here, although no emergency had been encountered in all the four years of the vessel's life, they found everything in readiness, and the two soon had prepared and eaten a hearty luncheon.

"Well, I can't think of any more excuses for monopolizing you, Miss Newton, so I suppose I'll have to take you back. Believe me, I've enjoyed this more than you can realize—I've...."

He broke off and listened, every nerve taut. "What was that?" he exclaimed.

"What was what? I didn't hear anything?"

"Something screwy somewhere! I felt a vibration, and anything that'd make this mountain of steel even quiver must have given us one gosh-awful nudge. There's another!"

The girl, painfully tense, felt only a barely perceptible tremor, but the computer, knowing far better than she the inconceivable strength and mass of that enormous structure of solidly braced hardened steel, sprang into action. Leaping to the small dirigible look-out plate, he turned on the power and swung it upward.

"Great suffering snakes!" he ejaculated, then stood mute, for the plate revealed a terrible sight. The entire nose of the gigantic craft had been sheared off in two immense slices as though clipped off by a gigantic sword, and even as they stared, fascinated, at the sight, the severed slices were drifting slowly away. Swinging the view along the plane of cleavage, Stevens made out a relatively tiny ball of metal, only fifty feet or so in diameter, at a distance of perhaps a mile. From this ball there shot a blinding plane of light, and the Arcturus fell apart at the midsection, the lower half separating clean from the upper portion, which held the passengers. Leaving the upper half intact, the attacker began slicing the lower, driving half into thin, disk-shaped sections. As that incandescent plane of destruction made its first flashing cut through the body of the Arcturus, accompanied by an additional pyrotechnic display of severed and short-circuited high-tension leads, Stevens and Nadia suddenly found themselves floating weightless in the air of the room. Still gripping the controls of the look-out plate, Stevens caught the white-faced girl with one hand, drew her down beside him, and held her motionless while his keen mind flashed over all the possibilities of the situation and planned his course of action.

"They're apparently slicing us pretty evenly, and by the looks of things, one cut is coming right about here," he explained rapidly, as he found a flashlight and drew his companion through the door and along a narrow passage. Soon he opened another door and led her into a tiny compartment so low that they could not stand upright—a mere cubicle of steel. Carefully closing the door, he fingered dials upon each of the walls of the cell, then folded himself up into a comfortable position, instructed Nadia to do the same, and snapped off the light.

"Please leave it on," the shaken girl asked. "It's so ghastly!"

"We'd better save it, Nadia," he advised, pressing her arm reassuringly, "it's the only light we've got, and we may need it worse later on—its life is limited, you know."

"Later on? Do you think we'll need anything—later on?"

"Sure! Of course they may get us, Nadia, but this little tertiary air-break is a mighty small target for them to hit. And if they miss us, as I think they will, there's a larger room opening off each wall of this one—at least one of which will certainly be left intact. From any one of those rooms we can reach a life-boat. Of course, it's a little too much to expect that any one of the life-boats will be left whole, but they're bulkheaded, too, you know, so that we can be sure of finding something able to navigate—providing we can make our get-away. Believe me, ace, I'm sure glad we're aboard the old Arcturus right now, with all her safety-devices, instead of on one of the modern liners. We'd be sunk right."

"I felt sunk enough for a minute—I'm feeling better now, though, since you are taking it so calmly."

"Sure—why not? A man's not dead until his heart stops beating, you know—our turn'll come next, when they let up a little."

"But suppose they change the width of their slices, and hit this cubby, small as it is?"

"It'd be just too bad," he shrugged. "In that case, we'd never know what hit us, so it's no good worrying about it. But say, we might do something at that, if they didn't hit us square. I can move fairly fast, and might be able to get a door open before the loss of pressure seals it. We'll light the flash ... here, you hold it, so that I can have both hands free. Put both arms around me, just under the arms, and stick to me like a porous plaster, because if I have to move at all, I'll have to jump like chain lightning. Shine the beam right over there, so it'll reflect and light up all the dials at once. There ... hold on tight! Here they come!"

As he spoke, a jarring shudder shook one side of their hiding-place, then, a moment later, the phenomenon was repeated, but with much less force, upon the other side. Stevens sighed with relief, took the light, and extinguished it.

"Missed us clean!" he exulted. "Now, if they don't find us, we're all set."

"How can they possibly find us? I seem to be always worried about the wrong things, but I should think that their finding us would be the least of our troubles."

"Don't judge their vision system by ours—they've got everything, apparently. However, their apparatus may not be delicate enough to spot us in a space this small when their projectors flash through it, as they probably will. Then, too, there's a couple of other big items in our favor—nobody else is in the entire lower half, since all this machinery down here is either automatic or else controlled from up above, so they won't be expecting to see anybody when they get down this far; and we aren't at all conspicuous. We're both dressed in gray—your clothes in particular are almost exactly the color of this armor-plate—so altogether we stand a good chance of being missed."

"What shall we do now?"

"Nothing whatever—wish we could sleep for a couple of hours, but of course there's no hope of that. Stretch out here, like that—you can't rest folded up like an accordion—and I'll lie down diagonally across the room. There's just room for me that way. That's one advantage of weightlessness—you can lie down standing on your head, and go to sleep and like it. But I forgot—you've never been weightless before, have you? Does it make you sick?"

"Not so much, now, except that I feel awfully weird inside. I was horribly dizzy and nauseated at first, but it's going away."

"That's good—it makes lots of people pretty sick. In fact, some folks get awfully sick and can't seem to get used to it at all. It's the canals in the inner ear that do most of it, you know. However, if you're as well as that already, you'll be a regular spacehound in half an hour. I've been weightless for weeks at a stretch, out in the Sirius, and now I've got so I really like it. Here, we'd better keep in touch." He found her hand and tucked it under his arm. "Stabilize our positions more, besides keeping us from getting too lonesome, here in the dark," he concluded, in a matter-of-fact voice.

"Thanks for saying 'us'—but you would, wouldn't you?" and a wave of admiration went through her for the real and chivalrous manhood of the man with whom she had been forced by circumstances to cast her lot. "How long must we stay here?"

"As long as the air lasts, and I'd like to stay here longer than that. We don't want to move around any more than we absolutely have to until their rays are off of us, and we have no way of knowing how long that will be. Also, we'd better keep still. I don't know what kind of an audio system they've got, but there's no use taking unnecessary chances."

"All x—I'm an oyster's little sister," and for many minutes the two remained motionless and silent. Now and then Nadia twitched and started at some vague real or imaginary sound—now and then her fingers tightened upon his biceps—and he pressed her hand with his great arm in reassurance and understanding. Once a wall of their cell resounded under the impact of a fierce blow and Stevens instantly threw his arm around the girl, twisting himself between her and the threatened wall, ready for any emergency. But nothing more happened; the door remained closed, the cell stayed bottle-tight, and time wore slowly on. All too soon the unmistakable symptoms of breathing an unfit atmosphere made themselves apparent and Stevens, after testing each of the doors, drew the girl into a larger room, where they breathed deeply of the fresh, cool air.

"How did you know that this room was whole?" asked Nadia. "We might have stepped out into space, mightn't we?"

"No; if this room had lost its tightness, the door wouldn't have opened. They won't open if there's a difference of one kilogram pressure on the two sides. That's how I knew that the room we were in at first was cut in two—the door into that air-break wouldn't move."

"What comes next?"

"I don't know exactly what to do—we'd better hold a little council of war. They may have gone..." Stevens broke off as the structure began to move, and they settled down upon what had been one of the side-walls. Greater and greater became the acceleration, until their apparent weight was almost as much as it would have been upon the Earth, at which point it became constant. "... but they haven't," he continued the interrupted sentence. "This seems to be a capture and seizure, as well as an attack, so we'll have to take the risk of looking at them. Besides, it's getting cold in here. One or two of the adjoining cells have apparently been ruptured and we're radiating our heat out into space, so we'll have to get into a life-boat or freeze. I'll go pick out the best one. Wonder if I'd better take you with me, or hide you and come back after you?"

"Don't worry about that—I'm coming with you," Nadia declared, positively.

"Just as well, probably," he assented, and they set out. A thorough exploration of all the tight connecting cells revealed that not a lifeboat within their reach remained intact, but that habitable and navigable portions of three such craft were available. Selecting the most completely equipped of these, they took up their residence therein by entering it and closing the massive insulating door. Stevens disconnected all the lights save one, and so shielded that one before turning it on that it merely lightened the utter darkness into a semi-permeable gloom. He then stepped up to the lookout plate, and with his hand upon the control, pondered long the possible consequences of what he wished to do.

"What harm would it do to take just a little peek?"

"I don't know—that's the dickens of it. Maybe none, and then again, maybe a lot. You see, we don't know who or what we are up against. The only thing we know is that they've got us beat a hundred ways, and we've got to act accordingly. We've got to chance it sometime, though, if we can ever get away, so we might as well do it now. I'll put it on very short range first, and see what we can see. By the small number of cells we've got here I'm afraid they've split us up lengthwise, too—so that instead of having a whole slice of the old watermelon to live in, we've got only about a sixth of one—shaped about like a piece of restaurant pie. One thing I can do, though. I'll turn on the communicator receiver and put it on full coverage—maybe we can hear something useful."

Putting a little power upon the visiray plate, he moved the point of projection a short distance from their hiding-place, so that the plate showed a view of the wreckage. The upper half of the vessel was still intact, the lower half a jumble of sharply-cut fragments. From each of the larger pieces a brilliant ray of tangible force stretched outward. Suddenly their receiver sounded behind them, as the high-powered transmitter in the telegraph room tried to notify headquarters of their plight.

"Arcturus attacked and cut up being taken tow...."

Rapidly as the message was uttered the transmitter died with a rattle in the middle of a word, and Nadia looked at Stevens with foreboding in her eyes.

"They've got something, that's one thing sure, to be able to neutralize our communicator beams that way," he admitted. "Not so good—we'll have to play this close to our vests, girl!"

"Are you just trying to cheer me up, or do you really think we have a chance?" she demanded. "I want to know just where we stand."

"I'm coming clean with you, no kidding. If we can get away, we'll be all x, because I'll bet a farm that by this time Brandon's got everything those birds have, and maybe more. They beat us to it, that's all. I'm kind of afraid, though, that getting away isn't going to be quite as simple as shooting fish down a well."

Far ahead of them a port opened, a lifeboat shot out at its full power, and again their receiver tried to burst into sound, but it was a vain attempt. The sound died before one complete word could be uttered, and the lifeboat, its power completely neutralized by the rays of the tiny craft of the enemy, floated gently back toward the mass of its parent and accompanied it in its headlong flight. Several more lifeboats made the attempt, as the courageous officers of the Arcturus, some of whom had apparently succeeded in eluding the vigilance of the captors, launched the little shells from various ports; but as each boat issued, its power was neutralized and it found itself dragged helplessly along in the grip of one of those mysterious, brilliant rays of force. At least one hidden officer must have been watching the fruitless efforts, for the next lifeboat to issue made no attempt, either to talk or to flee, but from it there flamed out into space a concentrated beam of destruction—the terrible ray of annihilation, against which no known substance could endure for a moment; the ray which had definitely outlawed war. But even that frightful weapon was useless—it spent its force harmlessly upon an impalpable, invisible barrier, a hundred yards from its source, and the bold lifeboat disappeared in one blinding explosion of incandescence as the captor showed its real power in retaliation. Stevens, jaw hard-set, leaped from the screen, then brought himself up so quickly that he skated across the smooth steel floor. Shutting off the lookout plate, he led the half-fainting girl across the room to a comfortable seat and sat down beside her—raging, but thoughtful. Nadia soon recovered.

"Why are you acting so contrary to your nature—is it because of me?" she demanded. "A dozen times I've seen you start to do something and then change your mind. I will not be a load on you nor hinder you in anything you want to do."

"I told your father I'd look after you, and I'm going to do it," he replied, indirectly. "I would do it anyway, of course—even if you are ten or twelve years older than I thought you were."

"Yes, Dad never has realized that I'm more than eight years old. I see—you were going out there and be slaughtered?" He flushed, but made no reply. "In that case I'm glad I'm here—that would have been silly. I think we'd better hold that council of war you mentioned a while ago, don't you?"

"I need a smoke—do you indulge?"

"No thanks. I tried it a few times at school, but never liked it."

He searched his pockets, bringing to light an unopened package and a tattered remnant which proved to contain one dilapidated cigarette. He studied it thoughtfully. "I'll smoke this wreck," he decided, "while it's still smokable. We'll save the rest of them—I'm afraid it'll be a long time between smokes. Well, let's confer!"

"This will have to be a one-sided conference. I don't imagine that any of my ideas will prove particularly helpful. You talk and I'll listen.

"You can't tell what ideas may be useful—chip in any time you feel the urge. Here's the dope, as I see it. They're highly intelligent creatures and are in all probability neither Martians nor Venerians. If any of them had any such stuff as that, some of us would have known about it and, besides, I don't believe they would have used it in just that way. Mercury is not habitable, at least for organic beings; and we have never seen any sign of any other kind of inhabitants who could work with metals and rays. They're probably from Jupiter, although possibly from further away. I say Jupiter, because I would think, judging from the small size of the ship, that it may still be in the experimental stage, so that they probably didn't come from any further away than Jupiter. Then, too, if they were very numerous, somebody would have sighted one before. I'd give my left leg and four fingers for one good look at the inside of that ship."

"Why didn't you take it, then? You never even looked toward it, after that one first glimpse."

"I'll say I didn't—the reason being that they may have automatic detectors, and as I have suggested before, our system of vision is so crude that its use could be detected with a clothesline or a basket full of scrap iron. But to resume: Their aim is to capture, not destroy, since they haven't killed anybody except the one crew that attacked them. Apparently they want to study us or something. However, they don't intend that any of us shall get away, nor even send out a word of what has happened to us. Therefore it looks as though our best bet is to hide now, and try to sneak away on them after a while—direct methods won't work. Right?"

"You sound lucid. Is there any possibility of getting back, though, if we got anywhere near Jupiter? It's so far away!"

"It's a long stretch from Jupiter to any of the planets where we have power-plants, all right—particularly now, when Mars and Tellus are subtending an angle of something more than ninety degrees at the sun, and Venus is between the two, while Jupiter is clear across the sun from all three of them. Even when Jupiter is in mean opposition to Mars, it is still some five hundred and fifty million kilometers away, so you can form some idea as to how far it is from our nearest planet now. No, if we expect to get back under our own power, we've got to break away pretty quick—these lifeboats have very little accumulator capacity, and the receptors are useless above about three hundred million kilometers...."

"But it'll take us a long time to go that far, won't it?"

"Not very. Our own ships, using only the acceleration of gravity, and both plus and minus at that, make the better than four hundred million kilometers of the long route to Mars in five days. These birds are using almost that much acceleration, and I don't see how they do it. They must have a tractor ray. Brandon claimed that such a thing was theoretically possible, but Westfall and I couldn't see it. We ragged him about it a lot—and he was right. I thought, of course, they'd drift with us, but they are using power steadily. They've got some system!"

"Suppose they could be using intra-atomic energy? We were taught that it was impossible, but you've shattered a lot of my knowledge today."

"I wouldn't want to say definitely that it is absolutely impossible, but the deeper we go into that line, the more unlikely intra-atomic energy power-plants become. No, they've got a real power-transmission system—one that can hold a tight beam together a lot farther than anything we have been able to develop, that's all. Well, we've given them quite a lot of time to get over any suspicion of us, let's see if we can sneak away from them."

By short and infrequent applications of power to the dirigible projectors of the life-boat, Stevens slowly shifted the position of the fragment which bore their craft until it was well clear of the other components of the mass of wreckage. He then exerted a very small retarding force, so that their bit would lag behind the procession, as though it had accidently been separated. But the crew of the captor was alert, and no sooner did a clear space show itself between them and the mass than a ray picked them up and herded them back into place. Stevens then nudged other pieces so that they fell out, only to see them also rounded up. Hour after hour he kept trying—doing nothing sufficiently energetic to create any suspicion, but attempting everything he could think of that offered any chance of escape from the clutches of their captors. Immovable at the plate, his hands upon the controls, he performed every insidious maneuver his agile brain could devise, but he could not succeed in separating their vehicle from its fellows. Finally, after a last attempt, which was foiled as easily as were its predecessors, he shut off his controls and turned to his companion with a grin.

"I didn't think I could get away with it—they're keen, that gang—but I had to keep at it as long as it would have done us any good."

"Wouldn't it do us any good now?"

"Not a bit—we're going so fast that we couldn't stop—we're out of even radio range of our closest power-plant. We'll have to put off any more attempts until they slow us down. They're fairly close to at least one of the moons of Jupiter, we'll have our best chance—so good, in fact, that I really think we can make it."

"But what good would that do us, if we couldn't get back?" Dire foreboding showed in her glorious eyes.

"Lots of things not tried yet, girl, and we'll try them all. First, we get away. Second, we try to get in touch with Norman Brandon...."

"How? No known radio will carry half that far."

"No, but I think that a radio as yet unknown may be able to—and there is a bare possibility that I'll be able to communicate."

"Oh wonderful—that lifts a frightful load off my mind," she breathed.

"But just a minute—I said I'd come clean with you, and I will. The odds are all against us, no matter what we do. If that unknown radio won't work—and it probably won't—there are several other things we can try, but they're all pretty slim chances. Even if we get away, it'll probably be about the same thing as though you were to be marooned on a desert island without any tools, and with your rescue depending upon your ability to build a high-powered radio station with which to call to a mainland for help. However, if we don't try to get away, our only alternative is letting them know we're here, and joining our friends in captivity."

"And then what?"

"You know as much as I do. Imprisonment and restraint, certain; death, possible; return to Earth, almost certainly impossible—life as guests, highly improbable."

"I'm with you, Steve, all the way."

"Well, it's time to spring off—we've both been awake better than fifty hours. Personally, I'm all in, and you're so near dead that you're a physical wreck. We'll get us a bite of supper and turn in."

An appetizing supper was prepared from the abundant stores and each ate a heartier meal than either would have believed possible. Stevens considered his unopened package of cigarettes, then regretfully put it back into his pocket still unopened and turned to Nadia.

"Well, little fellow, it's time to shove off, and then some. You might as well sleep here, and I'll go in there. If anything scares you, yell. Good-night, old trapper!"

"Wait a minute, Steve." Nadia flushed, and her brown eyes and black eyebrows, in comparison with her golden-blond hair, lent her face a quizzical, elfin expression that far belied her feelings as she stared straight into his eyes. "I've never even been away from the Earth before, and with all this happening I'm simply scared to death. I've been trying to hide it, but I couldn't stand it alone, and we're going to be together too long and too close for senseless conventions to affect us. There's two bunks over there—why don't you sleep in one of them?"

He returned her steadfast gaze for a moment in silence.

"All x with me, Nadia," he answered, keeping out of his voice all signs of the tenderness he felt for her, and of his very real admiration for her straightforward conduct in a terrifying situation. "You trust me, then?"

"Trust you! Don't be silly—I know you! I know you, and I know Brandon and Westfall—I know what you've done, and exactly the kind of men you are. Trust you!"

"Thanks, old golf-shootist," and promises were made and received in a clasp from which Nadia's right hand, strong as it was, emerged slightly damaged.

"By the way, what is your first name, fellow-traveller?" she asked in lighter vein. "Nobody, not even Dad or Breckie, ever seems to call you anything but 'Steve' when they talk about you." She was amazed at the effect of her innocent question, for Stevens flushed to his hair and spluttered.

"It's Percy!" He finally, snorted. "Percival Van Schravendyck Stevens. Wouldn't that tear it?"

"Why, I think Percival's a real nice name!"

"Silence!" he hissed in burlesque style. "Young woman, I have revealed to you a secret known to but few living creatures. On your life, keep it inviolate!"

"Oh, very well, if you insist. Good-night—Steve!" and she gave him a radiant and honest smile: the first smile he had seen since the moment of the attack.